X-ray Attenuation Property of Dendrimer-Entrapped Gold Nanoparticles

Abstract

We report the X-ray attenuation property of dendrimer-entrapped gold nanoparticles (Au DENPs) that could be used as a computed tomography (CT) contrast agent. Amine-terminated generation 5 (G5.NH2) poly(amidoamine) dendrimers were used as templates to complex AuCl4− ions for subsequent reductive formation of Au DENPs using sodium borohydride as a reducing agent. By varying the molar ratio between gold salt to G5.NH2, Au DENPs with a size range of 2−4 nm can be prepared. The formed Au DENPs are not only stable in water, PBS buffer, and cell culture media but also at different temperatures (from 4 to 50 °C) and different pH conditions (pH 5−8). X-ray absorption coefficient measurements show that the attenuation of Au DENPs is much higher than that of the iodine-based contrast agent at the same molar concentration of the active element (Au versus iodine). Furthermore, CT scanning showed significant enhancement at the point of mice injected subcutaneously with Au DENPs, and intravenous injection of acetylated Au DENPs enabled the X-ray CT imaging of mice, rendering them a promising contrast agent in CT imaging applications.